package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        // 缓存穿透方式 这里时自定义的工具类的使用方法
//        Shop shop = cacheClient.queryWithPassThrough(
//                CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.SECONDS);
        // 互斥锁方式
//        Shop shop = queryWithMutex(id);
        //逻辑过期方式
        Shop shop = cacheClient.queryWithLogicalExpire(
                CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.SECONDS
        );
        return Result.ok(shop);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            // 验证id，确保能够删除缓存
            return Result.fail("店铺id不存在");
        }
        // 1 更新数据库
        updateById(shop);
        // 2 删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);

        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1、判断是否需要根据坐标查询
        if(x == null || y == null){
            Page<Shop>page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }
        // 2、计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        // 3、查询redis 距离排序 分页 --> shopId  distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo() //GEOSEARCH  BYLONLAT x y  BYRADIUS 10 WITHDISTANCE
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4、解析id
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> content = results.getContent();
        // 防止末尾页报错，防止skip后导致的变量为空
        if (content.size() <= from){
            return Result.ok(Collections.emptyList());
        }
        // 4.1 截取from - end 的部分
        List<Long> ids = new ArrayList<>(content.size());
        Map<String, Distance> distanceMap = new HashMap<>(content.size());

        content.stream().skip(from).forEach(result -> {
            // 获取id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5、根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for(Shop shop : shops){
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 返回
        return Result.ok(shops);
    }


    // 缓存穿透
    public Shop queryWithPassThrough(Long id) {
        // 1、从redis查
        String shopKey = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(shopKey);
        // 2、判断
        if(StrUtil.isNotBlank(shopJson)){
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        // 判断命中是否是空值
        if(shopJson != null){
            // 返回错误信息
            return null;
        }
        // 不存在， 到数据库查
        Shop shop = getById(id);
        // 还是不存在，返回错误
        if(shop == null){
            // 将空值写入redis
            stringRedisTemplate.opsForValue()
                    .set(shopKey, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }

        // 存在， 写入redis
        stringRedisTemplate.opsForValue()
                .set(shopKey, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    // 线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    // 使用逻辑过期方式解决缓存击穿
    public Shop queryWithLogicalExpire(Long id){
        // 1、从redis查
        String shopKey = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(shopKey);
        // 2、判断
        if(StrUtil.isBlank(shopJson)){
            // 不存在则返回空
            return null;
        }
        // 反序列化
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject)redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 需要查看过期字段判断过期时间
        if(expireTime.isAfter(LocalDateTime.now())){
            // 未过期
            return shop;
        }
        // 过期，进行 缓存重建
        // 1、取锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        // 判断取锁是否成功
        if(isLock){
            //成功则开启线程进行重建数据
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    // 重建进程
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    // 释放锁
                    unlock(lockKey);
                }
            });

        }
        //     失败就返回      返回过期商铺信息
        return shop;
    }


    // 以互斥锁的方式解决缓存击穿问题
    public Shop queryWithMutex(Long id) {
        // 1、从redis查
        String shopKey = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(shopKey);
        // 2、判断
        if(StrUtil.isNotBlank(shopJson)){
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        // 判断命中是否是空值
        if(shopJson != null){
            // 返回错误信息
            return null;
        }
        // *实现缓存重建
        // 1、获取锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            // 2、判断锁是否获取成功
            if(!isLock){
                // 获取失败  休眠  与  重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            // 取锁成功， 到数据库查
            shop = getById(id);
            // 模拟延时
//            Thread.sleep(200);
            // 还是不存在，返回错误
            if(shop == null){
                // 将空值写入redis
                stringRedisTemplate.opsForValue()
                        .set(shopKey, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }

            // 存在， 写入redis
            stringRedisTemplate.opsForValue()
                    .set(shopKey, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // 4、释放锁
            unlock(lockKey);
        }

        return shop;
    }
    // 利用setnx 只在key不存在是才执行的特性模拟上锁
    private boolean tryLock(String key){
        Boolean lock = stringRedisTemplate.opsForValue()
                .setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.SECONDS);

        return BooleanUtil.isTrue(lock);
    }
    // 释放锁
    private void unlock(String key){
        stringRedisTemplate.delete(CACHE_SHOP_KEY + key);
    }

    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        // 查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        // 封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY +id, JSONUtil.toJsonStr(redisData));
    }




}
